Reminiscent of the skeletal features seen in patients with SPENCD, these defects include disorganized growth plates indicative of a role for TRAP in endochondral ossification, and mild osteopetrosis due to a resorptive defect of osteoclasts resulting in defective bone remodelling. The gene discussed is ACP5; the disease is Spondyloenchondrodysplasia with immune dysregulation.